The present invention relates generally to circuit boards and more particularly to an overall heat dissipating printed circuit board assembly which is especially suitable for high voltage or high voltage-to-ground applications and which, for reasons of efficiency, utilizes electrically conductive heat dissipating means in a preferred embodiment, specifically aluminum.
Conventional printed circuit boards do not normally include distinct heat dissipating arrangements such as air cooling arrangements, especially those circuit boards carrying circuits designated to operated at high voltages. In fact, to applicant's knowledge, those circuit boards which are designed to operate at high voltages do not include specific heat dissipating structure but, at most, are air cooled during operation. However, even this is not typically provided since air cooling has the tendency to draw in dust from the ambient surroundings which can accumulate within the cracks and crevices of the surrounding electronic components comprising part of the circuit board. Moreover, circuit boards which are air cooled cannot be readily encapsulated and thereby sealed from the dust and other foreign particles within its ambient surroundings.
As will be seen hereinafter, the present invention is directed to an overall circuit board assembly including a circuit board and specific heat dissipating structure for transferring heat generated at the circuit board by its electronic components to a remote location. As will also be seen, for reasons of efficiency, this structure includes electrically conductive heat dissipating means in a preferred embodiment, specifically an aluminum heat dissipating block adapted for connection to an adjacent thermally conductive frame.
While the utilization of aluminum or similar electrically conductive material for heat dissipation is certainly efficient from a heat transfer standpoint, it does raise certain problems if it is connected to an electrically conductive ground frame, which is typically the case. In doing this, however, the heat dissipating block also serves as a potential ground to the operating voltage on the printed circuit board which could disrupt the operation of its circuitry. This may be especially true with respect to circuitry operating at relatively high voltage. It may also be true with respect to circuits which operate at low floating voltages (high voltages but a low differential voltage) which display a relatively high voltage-to-ground level. However, in accordance with the present invention, the heat dissipating structure of applicant's overall assembly is specifically designed in a way which reliably provides high voltage standoff between the operating circuitry and the electrically conductive heat dissipating block sufficient to prevent the latter from inadvertantly grounding the circuitry and disrupting operation of the latter.